Information obtainable by electron microscopy will be applied to microorganismal structure directly, and as supplementary to data on function, chemical, and antigenic composition. Subjects of study will be streptococci (Groups A, B, and H) and their bacteriophages, mycoplasmas (including some of plant origin), and their viruses, gonococci, bacilli, staphylococci, and a variety of gram-negative bacteria. Specific areas of interest include phage morphology and distribution, cellular location of lipoteichoic acids phagocytosis, and the nature of subcellular organelles and formed elements.